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RE: [IP] MiniMed not registering Active Insulin



<<<I bolus 8 units for a meal
I then test BS, BS sent to pump
I then tell pump using the Bolus Wizard what the carbs were
With my ratios the answer was 7.6
It suggests I take 7.6>>>

It sounds like the wizard is working exactly as it is intended.  You're 
supposed to program in the number of carbs before you give a bolus, not 
program in the number of carbs after you give the bolus.  The wizard can't 
know that the 8 units you just gave were for the carbs that you later 
programmed in.  It thinks that the 8 units that were already programmed in 
were for something else, even though you didn't tell it what it was for 
(more carbs, a high BG, missing basal).  The wizard thinks that you are 
consuming an additional amount of carbs equal to another 8ish units of 
insulin.  The wizard does not subtract remaining insulin from a second bolus 
for a new source of carbs, only for a high or low BG.  The wizard thinks 
that any previous insulin is working on food that you already consumed, and 
by entering more carbs, you are consuming more food.  It is done this way so 
that you can bolus effectively when you are eating food in more a grazing 
motion, kind of like when you eat out at restaurants or at a party.

For example, you have 20 g carbs in the appetizer and you bolus for 20 g 
carbs.  20 minutes later your meal comes and you have 60 g carbs and you 
give a second bolus for the 60 g carbs (which you would certainly want to 
get the full amount for even though most of the previous bolus is still 
active--if the wizard subtracted the IOB, then you would effectively only 
bolus for 40 g of your meal and not 60 g).  30 minutes after that you decide 
that want desert which is another 50 g carbs (at this point if the wizard 
were to subtract the IOB, it would not suggest that you take any insulin for 
the remaining 50 g carbs).  So instead of giving enough insulin to cover 130 
g (20g+60g+50g) of carbs, if the wizard subtracted the IOB, then for the 
meal that you just ate, the wizard would have suggested that you only bolus 
for 60g of that total!  I don't know about you, but 70g of unbolused carbs 
would send me into the 400s or higher.

You do need to be aware when using the bolus wizard on ANY pump and take 
into consideration common sense.  It is possible to make a mistake 
calculating the number of carbs that you ate, or your body may just decide 
not digest the food that you just ate, or whatever.  The pump, as a machine, 
has to go by what you tell it and take that as absolute fact.  It can't 
think, "well I just delivered 8 units so the person programming into me must 
have already taken the insulin to cover what they are telling me that they 
are going to eat, so I won't suggest any insulin."  Instead, the pump is 
programmed to calculate "I delivered 8 units a few minutes ago.  Now they 
are telling me they are eating more carbs.  I need to suggest more insulin 
to cover those carbs."

On a side note, since you mentioned that you are using the MM512, the 
insulin on board calculations are not accurate anyway.  This pump assumes 
that insulin remains active for 8 hours, which almost all people find is way 
too long for fast acting insulin.  This problem was fixed in the MM515 pump 
(and the MM522 pump) so that you can put the active insulin time at around 
3-6 hours, which most people find much more accurate.  When I was using the 
MM512, sometimes I would find that if I gave a correction bolus before bed, 
the pump would think I still had active insulin in me when I woke up the 
next morning!

Hope this helps!

Sarah, dx'92, pumping'00
.
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